From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:54849 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752908AbbFWAsE (ORCPT ); Mon, 22 Jun 2015 20:48:04 -0400 Received: from epcpsbgr2.samsung.com (u142.gpu120.samsung.co.kr [203.254.230.142]) by mailout2.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NQD034ZKGW2KE80@mailout2.samsung.com> for linux-media@vger.kernel.org; Tue, 23 Jun 2015 09:48:02 +0900 (KST) Message-id: <5588ACC1.8010408@samsung.com> Date: Tue, 23 Jun 2015 09:48:01 +0900 From: Junghak Sung MIME-version: 1.0 To: Hans Verkuil , linux-media@vger.kernel.org Cc: mchehab@osg.samsung.com, sangbae90.lee@samsung.com, inki.dae@samsung.com, nenggun.kim@samsung.com, sw0312.kim@samsung.com Subject: Re: [RFC PATCH 0/3] Refactoring Videobuf2 for common use References: <1433770535-21143-1-git-send-email-jh1009.sung@samsung.com> <557AB99C.6030905@xs4all.nl> In-reply-to: <557AB99C.6030905@xs4all.nl> Content-type: text/plain; charset=windows-1252; format=flowed Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Hans, Thank you for your review. I reply to your comments. See below. Regards, Junghak On 06/12/2015 07:51 PM, Hans Verkuil wrote: > Hi Junghak, > > On 06/08/2015 03:35 PM, Junghak Sung wrote: >> Hello everybody, >> >> This patch series refactories exsiting Videobuf2, so that not only V4L2 >> but also other frameworks can use it to manage buffer and utilize >> queue. >> >> I would separate existing Videobuf2-core framework into two parts - common >> and v4l2-specific part. This work is as follows : >> >> 1. Separate existing vb2_buffer structure into common buffer and >> v4l2-specific parts by removing v4l2-specific members and >> embedding it into vb2_v4l2_buffer structure like this: >> >> struct vb2_v4l2_buffer { >> struct vb2_buffer vb2; >> struct v4l2_buffer v4l2_buf; >> struct v4l2_plane v4l2_planes[VIDEO_MAX_PLANES]; >> }; >> >> 2. Abstract the v4l2-specific elements, and specify them when the device >> drives use them. For example, vb2_v4l2_buffer structure can be abstracted >> by vb2_buffer structure, and device drivers can get framework-specific >> object such as vb2_v4l2_buffer by using container_of(). >> >> 3. Separate VB2-core framework into real VB2-core and v4l2-specific part. >> This means that it moves V4L2-specific parts of VB2-core to v4l2-specific >> part because current VB2-core framework has some codes dependent of V4L2. >> As a result, we will have two VB2 files - videobuf2-core.c and >> videobuf2-v4l2.c. >> >> Why do we try to make the VB2 framework to be common? >> >> As you may know, current DVB framework uses ringbuffer mechanism to demux >> MPEG-2 TS data and pass it to userspace. However, this mechanism requires >> extra memory copy because DVB framework provides only read() system call for >> application - read() system call copies the kernel data to user-space buffer. >> >> So if we can use VB2 framework which supports streaming I/O and buffer >> sharing mechanism, then we could enhance existing DVB framework by removing >> the extra memory copy - with VB2 framework, application can access the kernel >> data directly through mmap system call. >> >> This patch series is the first step for it. >> >> We have a plan for this work as follows: >> >> 1. Separate existing VB2 framework into three parts - VB2 common, VB2-v4l2, >> and VB2-dvb. Of course, this change should not affect other v4l2-based >> device drivers. This patch series includes some parts of this step. >> >> 2. Add new APIs for DVB streaming I/O. These APIs will be implemented >> in VB2-dvb framework. So, we can remove unnecessary memory copy between >> kernel-space and user-space by using these new APIs. >> However, we leaves legacy interfaces as-is for backward compatibility. >> >> We are working on this project with Mauro and have a discussion with him >> on IRC channel weekly. Nowaday, we are discussing more detailed DVB user >> scenario for streaming I/O. >> >> The final goal of this project is to enhance current DVB framework. >> The first mission is to achieve zero-copy functionality between kernel-space >> and user-space with mmap system call. More missions are under consideration: >> i.e., we could share the buffer not only between kernel-space and user-space >> but also between devices - demux, hw video codec - by exporting a buffer >> to dmabuf fd with VB2 framework. >> >> Any suggestions and comments are welcome. > I've tried to review it, but in the current form it is too hard to do. It's not > helped by the fact that patch 2 didn't make it to the mailinglist. It might > be better to just split up such large patches and make a note that the pull > request will combine the two (or more) patches into one. I agree with your opinion that the patches should be rework to be more easier to review. I will try to split up the patches and resend it. > BTW, I fully agree with what you want to do, where I am having trouble is > verifying that nothing breaks and in the details of the vb2 API changes. > > Can you make a new patch series that only shows the changes to the videobuf2 > sources and headers, so without all the driver changes? The driver changes > are automatically checked by the compiler when you build the drivers, so I > believe that that's correct (I hope :-) ). > > Also try to split it up in smaller pieces. I had the feeling that you combined > multiple but otherwise independent changes in one patch. The vb2 framework is > an important piece of code, and I want to be confident about the changes made. > > Regarding the split into core and v4l2 sources/headers: I've been thinking about > this a bit more, and what would probably make reviewing easiest is if you start > off with making a simple videobuf2-v4l2.h header that just includes core.h and > slowly move the v4l2-specific parts from videobuf2-core.h to videobuf2-v4l2.h. > > And do the same with videobuf2-v4l2.c: start off with an empty source and move > code from core.c to v4l2.c whenever a v4l2-specific part migrates. That's a good point. I think I have made these patches too hastily. As your comment, I will split the patch into two or more pieces. The first is just renaming videobuf2-core.[ch] to videobuf2-v4l2.[ch]. > Another note: I noticed that the queue_setup op was changed so the v4l2_format > argument became a void *. I do not think that that is the right approach since > we lose strong typing. > > I wonder if v4l2-specific queue ops should be introduced. I'm not sure how that > would work out, but I think we can look at that for the next round of patches. OK, I will try to find out more reasonable way to make it commonly (not v4l2-specific) without changing the v4l2-specivic queue ops. > Regards, > > Hans > >> Best regards, >> Junghak >> >> Junghak Sung (3): >> modify the vb2_buffer structure for common video buffer and make >> struct vb2_v4l2_buffer >> move struct vb2_queue to common and apply the changes related with >> that Signed-off-by: Junghak Sung >> make vb2-core part with not v4l2-specific elements >> >> Documentation/video4linux/v4l2-pci-skeleton.c | 16 +- >> drivers/media/dvb-frontends/rtl2832_sdr.c | 13 +- >> drivers/media/pci/cx23885/cx23885-417.c | 13 +- >> drivers/media/pci/cx23885/cx23885-core.c | 4 +- >> drivers/media/pci/cx23885/cx23885-dvb.c | 12 +- >> drivers/media/pci/cx23885/cx23885-vbi.c | 17 +- >> drivers/media/pci/cx23885/cx23885-video.c | 19 +- >> drivers/media/pci/cx23885/cx23885.h | 2 +- >> drivers/media/pci/cx25821/cx25821-video.c | 20 +- >> drivers/media/pci/cx25821/cx25821.h | 2 +- >> drivers/media/pci/cx88/cx88-blackbird.c | 15 +- >> drivers/media/pci/cx88/cx88-core.c | 2 +- >> drivers/media/pci/cx88/cx88-dvb.c | 13 +- >> drivers/media/pci/cx88/cx88-mpeg.c | 2 +- >> drivers/media/pci/cx88/cx88-vbi.c | 17 +- >> drivers/media/pci/cx88/cx88-video.c | 17 +- >> drivers/media/pci/cx88/cx88.h | 2 +- >> drivers/media/pci/saa7134/saa7134-core.c | 4 +- >> drivers/media/pci/saa7134/saa7134-ts.c | 28 +- >> drivers/media/pci/saa7134/saa7134-vbi.c | 22 +- >> drivers/media/pci/saa7134/saa7134-video.c | 17 +- >> drivers/media/pci/saa7134/saa7134.h | 8 +- >> drivers/media/pci/solo6x10/solo6x10-v4l2-enc.c | 19 +- >> drivers/media/pci/solo6x10/solo6x10-v4l2.c | 11 +- >> drivers/media/pci/solo6x10/solo6x10.h | 4 +- >> drivers/media/pci/sta2x11/sta2x11_vip.c | 24 +- >> drivers/media/pci/tw68/tw68-video.c | 20 +- >> drivers/media/pci/tw68/tw68.h | 2 +- >> drivers/media/platform/am437x/am437x-vpfe.c | 33 +- >> drivers/media/platform/am437x/am437x-vpfe.h | 2 +- >> drivers/media/platform/blackfin/bfin_capture.c | 30 +- >> drivers/media/platform/coda/coda-bit.c | 20 +- >> drivers/media/platform/coda/coda-common.c | 28 +- >> drivers/media/platform/coda/coda-jpeg.c | 2 +- >> drivers/media/platform/coda/coda.h | 6 +- >> drivers/media/platform/davinci/vpbe_display.c | 25 +- >> drivers/media/platform/davinci/vpif_capture.c | 30 +- >> drivers/media/platform/davinci/vpif_capture.h | 2 +- >> drivers/media/platform/davinci/vpif_display.c | 34 +- >> drivers/media/platform/davinci/vpif_display.h | 6 +- >> drivers/media/platform/exynos-gsc/gsc-core.c | 2 +- >> drivers/media/platform/exynos-gsc/gsc-core.h | 6 +- >> drivers/media/platform/exynos-gsc/gsc-m2m.c | 12 +- >> drivers/media/platform/exynos4-is/fimc-capture.c | 23 +- >> drivers/media/platform/exynos4-is/fimc-core.c | 4 +- >> drivers/media/platform/exynos4-is/fimc-core.h | 6 +- >> drivers/media/platform/exynos4-is/fimc-is.h | 2 +- >> drivers/media/platform/exynos4-is/fimc-isp-video.c | 25 +- >> drivers/media/platform/exynos4-is/fimc-isp-video.h | 2 +- >> drivers/media/platform/exynos4-is/fimc-isp.h | 4 +- >> drivers/media/platform/exynos4-is/fimc-lite.c | 25 +- >> drivers/media/platform/exynos4-is/fimc-lite.h | 4 +- >> drivers/media/platform/exynos4-is/fimc-m2m.c | 14 +- >> drivers/media/platform/m2m-deinterlace.c | 16 +- >> drivers/media/platform/marvell-ccic/mcam-core.c | 26 +- >> drivers/media/platform/marvell-ccic/mcam-core.h | 2 +- >> drivers/media/platform/mx2_emmaprp.c | 16 +- >> drivers/media/platform/omap3isp/ispvideo.c | 24 +- >> drivers/media/platform/omap3isp/ispvideo.h | 4 +- >> drivers/media/platform/s3c-camif/camif-capture.c | 23 +- >> drivers/media/platform/s3c-camif/camif-core.c | 2 +- >> drivers/media/platform/s3c-camif/camif-core.h | 4 +- >> drivers/media/platform/s5p-g2d/g2d.c | 14 +- >> drivers/media/platform/s5p-jpeg/jpeg-core.c | 34 +- >> drivers/media/platform/s5p-mfc/s5p_mfc.c | 14 +- >> drivers/media/platform/s5p-mfc/s5p_mfc_common.h | 4 +- >> drivers/media/platform/s5p-mfc/s5p_mfc_dec.c | 36 +- >> drivers/media/platform/s5p-mfc/s5p_mfc_enc.c | 57 +- >> drivers/media/platform/s5p-mfc/s5p_mfc_opr_v5.c | 4 +- >> drivers/media/platform/s5p-mfc/s5p_mfc_opr_v6.c | 4 +- >> drivers/media/platform/s5p-tv/mixer.h | 4 +- >> drivers/media/platform/s5p-tv/mixer_reg.c | 2 +- >> drivers/media/platform/s5p-tv/mixer_video.c | 11 +- >> drivers/media/platform/sh_veu.c | 25 +- >> drivers/media/platform/soc_camera/atmel-isi.c | 26 +- >> drivers/media/platform/soc_camera/mx2_camera.c | 41 +- >> drivers/media/platform/soc_camera/mx3_camera.c | 34 +- >> drivers/media/platform/soc_camera/rcar_vin.c | 30 +- >> .../platform/soc_camera/sh_mobile_ceu_camera.c | 47 +- >> drivers/media/platform/soc_camera/soc_camera.c | 2 +- >> drivers/media/platform/ti-vpe/vpe.c | 30 +- >> drivers/media/platform/vim2m.c | 28 +- >> drivers/media/platform/vivid/vivid-core.h | 4 +- >> drivers/media/platform/vivid/vivid-kthread-cap.c | 8 +- >> drivers/media/platform/vivid/vivid-kthread-out.c | 8 +- >> drivers/media/platform/vivid/vivid-sdr-cap.c | 18 +- >> drivers/media/platform/vivid/vivid-vbi-cap.c | 14 +- >> drivers/media/platform/vivid/vivid-vbi-out.c | 14 +- >> drivers/media/platform/vivid/vivid-vid-cap.c | 24 +- >> drivers/media/platform/vivid/vivid-vid-out.c | 21 +- >> drivers/media/platform/vsp1/vsp1_rpf.c | 4 +- >> drivers/media/platform/vsp1/vsp1_video.c | 20 +- >> drivers/media/platform/vsp1/vsp1_video.h | 6 +- >> drivers/media/platform/vsp1/vsp1_wpf.c | 4 +- >> drivers/media/usb/airspy/airspy.c | 15 +- >> drivers/media/usb/au0828/au0828-vbi.c | 17 +- >> drivers/media/usb/au0828/au0828-video.c | 29 +- >> drivers/media/usb/au0828/au0828.h | 2 +- >> drivers/media/usb/em28xx/em28xx-vbi.c | 15 +- >> drivers/media/usb/em28xx/em28xx-video.c | 30 +- >> drivers/media/usb/em28xx/em28xx.h | 2 +- >> drivers/media/usb/go7007/go7007-driver.c | 2 +- >> drivers/media/usb/go7007/go7007-priv.h | 4 +- >> drivers/media/usb/go7007/go7007-v4l2.c | 15 +- >> drivers/media/usb/hackrf/hackrf.c | 13 +- >> drivers/media/usb/msi2500/msi2500.c | 13 +- >> drivers/media/usb/pwc/pwc-if.c | 26 +- >> drivers/media/usb/pwc/pwc.h | 2 +- >> drivers/media/usb/s2255/s2255drv.c | 16 +- >> drivers/media/usb/stk1160/stk1160-v4l.c | 15 +- >> drivers/media/usb/stk1160/stk1160-video.c | 2 +- >> drivers/media/usb/stk1160/stk1160.h | 4 +- >> drivers/media/usb/usbtv/usbtv-video.c | 11 +- >> drivers/media/usb/usbtv/usbtv.h | 2 +- >> drivers/media/usb/uvc/uvc_queue.c | 32 +- >> drivers/media/usb/uvc/uvcvideo.h | 4 +- >> drivers/media/v4l2-core/Makefile | 2 +- >> drivers/media/v4l2-core/v4l2-ioctl.c | 2 +- >> drivers/media/v4l2-core/v4l2-mem2mem.c | 8 +- >> drivers/media/v4l2-core/videobuf2-core.c | 1888 ++------------------ >> drivers/media/v4l2-core/videobuf2-dma-contig.c | 2 +- >> drivers/media/v4l2-core/videobuf2-dma-sg.c | 2 +- >> drivers/media/v4l2-core/videobuf2-dvb.c | 2 +- >> drivers/media/v4l2-core/videobuf2-memops.c | 2 +- >> drivers/media/v4l2-core/videobuf2-v4l2.c | 1878 +++++++++++++++++++ >> drivers/media/v4l2-core/videobuf2-vmalloc.c | 2 +- >> drivers/staging/media/davinci_vpfe/vpfe_video.c | 30 +- >> drivers/staging/media/davinci_vpfe/vpfe_video.h | 2 +- >> drivers/staging/media/dt3155v4l/dt3155v4l.c | 14 +- >> drivers/staging/media/dt3155v4l/dt3155v4l.h | 2 +- >> drivers/staging/media/omap4iss/iss_video.c | 16 +- >> drivers/staging/media/omap4iss/iss_video.h | 4 +- >> drivers/usb/gadget/function/uvc_queue.c | 14 +- >> drivers/usb/gadget/function/uvc_queue.h | 4 +- >> include/media/davinci/vpbe_display.h | 2 +- >> include/media/soc_camera.h | 2 +- >> include/media/v4l2-mem2mem.h | 10 +- >> include/media/videobuf2-core.h | 235 ++- >> include/media/videobuf2-dma-contig.h | 6 +- >> include/media/videobuf2-dma-sg.h | 6 +- >> include/media/videobuf2-dvb.h | 2 +- >> include/media/videobuf2-memops.h | 2 +- >> include/media/videobuf2-v4l2.h | 139 ++ >> include/media/videobuf2-vmalloc.h | 2 +- >> 144 files changed, 3290 insertions(+), 2662 deletions(-) >> create mode 100644 drivers/media/v4l2-core/videobuf2-v4l2.c >> create mode 100644 include/media/videobuf2-v4l2.h >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in